3.1. Introduction

Polar environmental changes are expected to be greater than for many other
places on Earth (IPCC 1996, WG II, Section 7.5). The Arctic and Antarctic contain
about 20% of the world's land area. Athough similar in many ways, the two polar
regions are different in that the Arctic is a frozen ocean surrounded by land,
whereas the Antarctic is a frozen continent surrounded by ocean. The Antarctic
is thermally isolated by the polar vortex, whereas the Arctic is influenced
by seasonal atmospheric transport from the surrounding continents.

The Antarctic, for the purposes of this document, comprises the Antarctic continent,
the surrounding Southern Ocean, south of 55�S, and the Sub-Antarctic islands
(e.g., Campbell Island, Heard Island, South Georgia Islands). It is the driest,
windiest, coldest, and cleanest continent and covers around 14 million km2 (UNEP,
1997). It is devoid of trees. Its boundary is sometimes taken to coincide with
the Antarctic Convergence, which roughly parallels the mean February air isotherm
of 10�C and is the northern boundary of the Antarctic marine ecosystem. The
area is managed by the Consultative Parties to the Antarctic Treaty to the dedication
of science and peace (UNEP, 1997.) The Arctic, for the purposes of this document,
is defined as the area within the Arctic Circle; it includes the boreal forests
and discontinuous permafrost, although some authors prefer to use the area north
of the natural tree line-which coincides approximately with the mean July air
isotherm of 10�C (Sugden, 1982). The Arctic areas of North America, Asia, and
Europe are included here, rather than in other regional chapters.

The polar regions are a zone marginal for the distribution of many species;
however, native organisms thrive in terrestrial and marine ecosystems. Apart
from research bases, the Antarctic is virtually uninhabited by humans. It is
the only continent without indigenous peoples (about 4,000 persons are there
for prolonged periods, engaged in scientific research). The Arctic, however,
has been populated for thousands of years by a variety of indigenous peoples
who have developed ways of life to adapt to the harsh and changing climate,
but at very low densities compared to the rest of the world. A number of urban
outposts have developed in recent times. There is a distinct contrast and sometimes
conflict between intrusive modern society and indigenous culture.

There is little resource use in the Antarctic and surrounding Southern Ocean
apart from fishing and tourism. These industries have been increasing in activity
over recent years and have considerable potential for growth. Although tourists
generally make visits of shorter duration, the number of tourists now is about
double the number of scientists. Antarctic tourism is growing rapidly; the expected
number of tourists might exceed 10,000 persons in the 1997-98 season (IAATO,
1997). Some local fish populations have been depleted, but the krill population
could become a food source even though the maximum harvest has only been on
the order of 500,000 tons. There is a multinational approach to natural resources
and environmental management, with minerals exploration and exploitation banned
by international agreement. By contrast, the Arctic lies within the political
boundaries of some of the world's richest and most powerful nations. There is
considerable economic activity based around fishing, farming and herding, oil
extraction, mining, and shipping. All of these activities are climate sensitive.
The Arctic has been a critical strategic area, and there still are considerable
defense establishments in the region.

Figure 3-1: Observed annual winter (DJF) temperature anomaly over
the Arctic during the period 1900-96.